The Long Term Evolution (LTE), Release 8 (Rel-8) of the Third Generation Partnership Project (3GPP) Universal Mobile Telecommunications System (UMTS) supports only single-layer beamforming on a single antenna port in the downlink. LTE release 9 (Rel-9) supports dual-layer beamforming using UE specific reference signals (RS) or dedicated reference signals (DRS) for both LTE-TDD and FDD in the downlink. With the introduction of dual-layer beamforming in LTE Rel-9, single-layer downlink transmission requires an indication of the antenna port to the UE within a DCI format supporting dual-layer or dual-antenna port transmission. The enhanced features and capabilities proposed for LTE Rel-9 should be backwards compatible with networks and user equipment (UE) compliant with LTE Rel-8 and should aim to be an extension of the beamforming in Rel-8. It has been agreed in 3GPP TSG (Technical Specification Group) RAN (Radio Access Network) Meeting #43 to at least introduce single user multi-input multi-output (SU-MIMO) in the defined frame work with the possible addition of enhancements for multi user multi-input multi-output (MU-MIMO) with beamforming in TSG RAN#44.
The various aspects, features and advantages of the invention will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Detailed Description thereof with the accompanying drawings described below. The drawings may have been simplified for clarity and are not necessarily drawn to scale.